Baynes shook his hand in visible pain and went to the locker room when play stopped.

Celtics coach Brad Stevens said after the 111-103 loss on Wednesday night that he could see the break on the X-ray.

Big man Al Horford has also been ruled out for Friday night's game against the Milwaukee Bucks. Guerschon Yabusele, Daniel Theis and rookie Robert Williams are expected to have increased responsibilities at center.